Glucose metabolism not only is the main energy source for cells, but also provides essential biomass for proliferating cells, including cancer cells [1]. Many diseases are associated with glucose transport and metabolic disorders, such as myocardial ischemia, type 2 diabetes and cancer [2]. In proliferating cells, especially cancer cells, the glucose metabolism is reprogrammed (Warburg Effect) to cater for unconstrained proliferation and invasion [1, 3-5]. Therefore, monitoring glucose metabolism of cells can provide important information that reflects a cell response to stimuli and proliferative states, which are extremely useful in cancer therapeutic diagnoses, in wound healing diagnoses and for fundamental understating of biological processes of the metabolism.
Glucose metabolism is composed of hundreds of reactions and metabolites; however, it can be simplified as below:

Focusing on these metabolites and enzymes, many assay kits and techniques have been developed to detect the metabolic changes that occur in cells, tissues or living bodies [6]. Some traditional assay techniques have also been applied to the detection of metabolic changes, such as high-performance liquid chromatography (HPLC), mass spectrometry (MS) and NMR spectroscopy [7-10]. For measuring glucose uptake, one available method is the radiometric assay, which is based on radiolabeled (3H, 14C) glucose [11, 12]. Due to the rapid metabolism of glucose in cells, the assay should be finished in a short time to avoid transporting the radiolabeled final products (H2O and CO2) out of cells. Therefore, researchers now prefer to use nonmetabolizable analogs of glucose, such as 3-o-methylglucose, 2-deoxyglucose (2-DG), fluoro-deoxyglucose (18F-FDG) and 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) [2, 14-16]. These nonmetabolizable analogs of glucose will form metabolic stress in the cells, which will induce cell death [17]. None of these methods provide a real-time direct assay for glucose metabolism in living cells or organisms.
Innumerable glucose sensors and devices have been developed by researchers in this field, including electrochemical glucose sensors [18], optical (fluorescence and absorbance) glucose sensors [19, 20] and glucose selective polymeric sensing fluid based on direct binding [21]. According to the method for recognition of glucose, Steiner et al. classified these sensors into five fundamental types [22]: type I based on the specific binding of glucose to enzymes/coenzymes, type it based on the detection of glucose metabolites produced by certain enzymes, type III based on the interaction between glucose and organic boronic acids, type IV based on concanavalin A (Con A) and type V based on other glucose binding proteins. Organic boronic acids can interact with 1,2- or 1,3-diols to form a complex of five or six membered cyclic esters in aqueous solution [22-27]. The interaction is reversible, which is ideal to “true sensor” design [22]. The reversible complexation is required for a sensor that can monitor the continuous change of target molecules. Shinkai and his colleagues developed organic boronic acids by a modification of anthracene with a bis-phenylboronic acid (GS-COOH, FIG. 1) and its derivatives, which possess photo-induced electron transfer (PET) effect [25, 26]. Because of the unique cleft-like structure, the compound GS and its related hydrogels showed high selectivity and sensitivity to glucose [25, 28, 29].